06/21/2015 09:04 EDT | Updated 06/21/2016 05:59 EDT

How The Bacteria Up Your Nose Affects Your Health

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At one time or another, we all encounter the frustration of a runny nose. The infiltration of a virus into our nasal passages can lead to days if not weeks of drips, sniffles and sneezes. The cause is usually microbial, such as a virus like the common cold. All we can seem to do is wait for the immune system to do its thing and then eventually clear the infection.

But viruses are not the only microbes capable of finding their way into the sinuses. A number of bacteria are also capable of not only living in this moist region, but thriving there as well. This collection is known as the nasal microbiome.

One of the first examinations into the nature of the bacteria living up our noses happened quite recently in 2010. The main focus at the time was on the prevalence of a particular species, Staphylococcus aureus and in particular, an antibiotic resistant version known as MRSA.

When the analyses were complete, the researchers found the microbial population differed between people meaning each might have their own nasal microbiome. But this wasn't the only discovery. The actual nature of the bacterial species could help to determine whether a person was more susceptible to MRSA infection. The data suggested there may be more good behind those nasal microbes than once thought including potentially a form of protection.

This latter point was shown last year in the lab through a rather inventive experiment. They used triclosan. It's the main ingredient in antibacterial soap and can be found in many personal grooming products. As expected the chemical had a deleterious effect by promoting the growth of S. aureus. They also discovered the same issue in rats. Essentially, triclosan hindered the ability of the natural microbiome to prevent this potentially infectious bacterium from attaching.

Of course, the protective effect of the microbiome could only go so far. Also last year,

this limitation was revealed when researchers tried to determine any links between the bacterial population and the occurrence of rhinovirus, one of the members of the common cold viruses. Unfortunately, the results showed natural bacteria present seemed to have no ability to prevent infection. The situation worsened as the virus allowed other bacteria, including pathogens, into the area.

The effect of external forces on the nasal microbiome in the short term prompted a look at longer term effects. In essence, could changes in the bacterial species in the nose be associated with disease. This was examined earlier this year as researchers examined the difference in microbial population between healthy individuals and those suffering from chronic sinusitis.

Their goal was to look for any differences in the microbial population between health and disease. Yet, when the results came back, they were somewhat surprising. The diversity in sick people was lower; this wasn't a surprise. But when they looked for any similarities in microbial species in sick people, there was simply no harmony.

The authors concluded the populations had to be defined in another manner, perhaps genetic or immunological. But when it came to disease, only diversity seemed to be associated with health. As to which factors contribute to the bacteria in our noses, the answer remained unclear.

Last week some of the answers were provided by an international team of researchers who undertook the effort to identify the reasons behind the nasal microbiome. Their method involved looking at the nasal populations of twins, both identical and fraternal. They hoped to find some type of genetic and possibly immune-based reasoning to explain the bugs in our noses.

The methods were relatively simple. The team collected nasal swabs from 46 identical and 43 fraternal twin pairs. The samples were then examined for presence of bacteria. As the lists were developed, they were compared not only to the twin but also to the rest of the population. This "big data" approach offered a larger picture of the potential factors involved.

Despite all the work, the results revealed no link between genetics and the microbial population. Every single person had a unique collection of bacteria. At best, there was a 25 per cent link. But the genetic makeup did seem to play a role in the actual number of bacteria present in the nose. There was also a difference between males and females. In essence, our genes can dictate density but in terms of which species are allowed to live there, it's out of our hands.

There was one result that could be used to improve health. There was a relationship between the levels of S. aureus and certain types of good bacteria. When they were present in high numbers, the potential pathogen couldn't thrive. This could potentially open the door for the development of nasal-based probiotics. By inserting these good bacteria up the nose, the risk of an infection can be reduced. Whether this will be the future of nose health remains to be seen.


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